Water-in-oil emulsion type blasting agent

ABSTRACT

A WATER-IN-OIL EMULSION TYPE BLASTING AGENT CONTAINING INORGANIC OXIDIZING SALT, NITROGEN-BASE SALT, WATER, WATERINSOLUBLE ORGANIC FUEL THAT FORMS A CONTINUOUS OIL PHASE, LIPOPHILIC EMULSIFIER AND GAS BUBBLES.

Patented July 4, 1972 Int. Cl. C06b 19/00 US. Cl. 149-2 10 ClaimsABSTRACT OF THE DISCLOSURE A water-in-oil emulsion type blasting agentcontaining inorganic oxidizing salt, nitrogen-base salt, water,waterinsoluble organic fuel that forms a continuous oil phase,lipophilic emulsifier and gas bubbles.

BACKGROUND OF THE INVENTION This invention relates to blasting agents inthe form of a water-in-oil emulsion and, more particularly, to suchblasting agents comprising an inorganic oxidizing salt, nitrogen-basesalt and gas bubbles incorporated in the explosive composition.

Ammonium nitrate-fuel oil compositions, often referred to as ANFO, arean inexpensive source of energy for blasting but have seriousshortcomings. These compositions cannot be used in wet boreholes unlessthey are packaged in waterproof containers or further processed.Furthermore, and more importantly, the explosive action and density ofANFO explosives are not sufficiently high for many commercial uses. Onthe other hand, thickened water-bearing explosives have been successfulcommercially because they can be used under a variety of conditions,e.g., in boreholes containing water, and they have good densities anddetonation velocities. These products typically comprise an oxidizingcomponent, e.g., ammonium nitrate, a fuel component dispersed ordissolved in an aqueous medium, which is thickened, usually by guar gumand, where premium performance is required, generally containsensitizers. The incorporation of thickeners, such as guar gum, andsensitizers such as TNT or aluminum in the explosive compositionincreases the cost of the blasting agent and, generally, results inproducts that do not adequately perform in small diameter holes or areundesirable from other standpoints. Accordingly, there is a need in theexplosives industry for a low-cost, high-velocity explosive compositionthat is readily formulated, water-resistant, safe to handle, and yetsufiiciently sensitive to allow propagation in small diameter holes and,preferably, is pumpable from a source of supply to a borehole. Thisinvention provides a water-in-oil emulsion type blasting agent meetingthe above-mentioned needs.

SUMMARY OF THE INVENTION The present invention provides a novel blastingagent in the form of a water-in-oil emulsion comprising inorganicoxidizing salt; nitrogen-base salt of an inorganic oxidizing acid and abase selected from the group consisting of: (1) acyclic nitrogen baseshaving no more than two hydrogen atoms bonded to the basic nitrogen andup to three carbon atoms per basic nitrogen, and (2) phenylamines;water; water-insoluble organic fuel that forms a continuous oil phase inthe blasting agent; lipophilic emulsifier for said fuel capable offorming and maintaining a stable water-in-oil emulsion, and 5 to 50% byvolume, gas bubbles incorporated in said blasting agent.

The combination of nitrogen-base salt and gas bubbles in thewater-in-oil emulsion, containing oxidizing salt and fuel, results in ablasting agent that is safe to handle yet especially sensitive todetonation and will propagate at high velocity in boreholes having adiameter as small as one or two inches. Quite surprisingly, the presentblasting agents have detonation velocities comparable to conventionalwater gels or slurry explosives containing substantial quantities ofhigh explosive. The blasting agents of the present invention arepourable or pumpable, if desired, and can vary in consistency over awide range from slightly viscous to a thick, tough, self-sustainingmass.

It is significant to note that in order for the composition to functionin small diameter holes, e.g. of the order of two inches, it isnecessary that sufficient gas bubbles and nitrogen-base salt areincorporated therein. The gas bubbles can be incorporated by anysuitable means such as injecting a gas into the composition,mechanically beating air into the blasting agent or adding particulatematerial thereto that entraps air. Preferably, the gas is usuallyincorporated in the explosive by adding to it solid aircarryingmaterial. such as microballons or silicious glass. The gas bubblescontained in the blasting agent are present in amounts of from about 5to 50% by volume and the nitrogen-base salt is present in amounts offrom 3 to 30% by weight of the total composition. The nitrogenbase saltincreases the sensitivity of the composition so that such compositionscan be used effectively in very small boreholes, for example, about twoinches or less in diameter, and reliably detonate and propagate andproduce high velocities of detonation.

The blasting agents of this invention can be formed by mixing an aqueoussolution of an inorganic oxidizing salt(s) alone or together withnitrogen-base salt with organic fuel containing a lipophilic emulsifier,agitating the mixture until a thickened emulsion is formed and thenincorporating gas, by the addition of gas-carrying matetial e.g.,microballons or injection of air, and obtaining a blasting agent in theform of a water-in-oil emulsion.

PREFERRED EMBODIMENTS OF THE INVENTION The inorganic oxidizing salt usedin the blasting agent of the present invention is usually present inamounts of from about 35 to 85%, preferably 45 to by weight of the totalcomposition. Examples of inorganic oxidizing salts include ammonium,alkali metal and alkaline earth metal nitrates, and perchlorates as wellas mixtures of two or more such salts. Representative compounds areammonium nitrate, ammonium perchlorate, sodium nitrate, sodiumperchlorate, potassium nitrate, potassium perchlorate, magnesiumnitrate, magnesium perchlorate and calcium nitrate. Preferably, theinorganic oxidizing salt present in the water phase in the compositionis ammonium nitrate alone or, in some instances, in combination with upto about 35% sodium nitrate.

The amount of water added to the composition is from about 10 to 35% byweight, and preferably, from about 15 to 25%. The water, containinginorganic oxidizing salt and nitrogen-base salt, forms the discontinuousaqueous phase of the water-in-oil emulsion blasting agent.

The nitrogen-base salt employed in the blasting agent can be derivedfrom inorganic bases such as hydrazines, but preferably they are derivedfrom amines, especially aliphatic amines and phenylamines. Phenylamines,as used herein refer to compounds having one carbocyclic aromatic ringto which is bonded at least one, and preferably one or two, primaryamino groups. Salts of primary, secondary and tertiary amines meetingthe aforementioned requirements can be used and the base moiety can bearsubstituents other than carbon, hydrogen and the base nitrogen that areinert with the system. The oxidizing acid moiety can be that of any ofthe strong inorganic oxidizing acids, preferably mineral acids, forexample, salts of nitric, nitrous, chloric and perchloric acid.Excellent exposive properties are obtained when the blasting agents ofthe present invention are used in boreholes having diameters of abouttwo inches. Such superior performance is due largely to the presence ofthe nitrogen-base salt.

Representative examples of nitrogen-base salts or amine nitrates thatcan. be incorporated in the present blasting agent include inorganicsalts such as hydrazine nitrate, dinitrate and perchlorate; salts ofaliphatic amines such as monomethylamine nitrate, nitrite, chlorate andperchlorate, ethylene diamine dinitrate and diperchlorate, dimethylaminenitrate, trimethylamine nitrate, ethylamine nitrate, propylaminenitrate, ethanolamine nitrate, guanadine nitrate, urea nitrate and saltsof phenylamines such as aniline nitrate, chlorate and perchlorate,p-chloroaniline nitrate and phenylenediamine dinitrate. Of theaforementioned salts saturated aliphatic amine nitrates containing up tothree carbon atoms, for example, monomethylamine nitrate, trimethylaminenitrate, ethylenediamine dinitrate and ethanolamine nitrate areparticularly preferred because of the ease of formulation of explosivestherewith and the outstanding explosive properties such as velocity andstrength of the resulting compositions. Mixtures of the aforementionedsalts can be used and generally, in such salt mixtures, the overalloxygen balance of the salt should be more positive than 150%.

The nitrogen-base salt can be incorporated in the composition insubstantially pure form; however, preferably it is provided as a crudereaction mixture of the base substantially neutralized with theoxidizing acid, either formed separately in aqueous medium then blendedwith the remainder of the constituents of the explosive or formed insitu in the presence of one or more of such constituents.

The total amount of nitrogen-base salt used varies with the particularcomposition and can range from about 3 to 30% by weight of the totalcomposition. Preferably, about 7 to 20% by weight of the nitrogen-basesalt is incorporated in the water-in-oil emulsion blasting agent.

The organic fuel that is used to form the continuous oil phase ischaracterized as being insoluble in water and is a liquid or solid, orblends thereof, which are liquid at the time of manufacture. The termoil means any hydrocarbon or substituted hydrocarbon that functions as afuel in the explosive reaction. Organic fuels forming the oil phase canbe present in the composition individually or in combination. Suitableorganic compounds that function as fuels forming the oil phase of theemulsion are hydrocarbon oils such as diesel oil, paraffin wax, talloil, long-chain fatty acids such as oleic acid, nitroalkanes such asnitropropane, aromatic hydrocarbons such as benzene, substitutedaromatic hydrocarbons such as nitrobenzene and also silicone oils andthe like. It is believed that the continuous phase of oil surrounds thecrystals of inorganic oxidizing salt, for example, ammonium nitrate, andretards crystal growth. Organic fuels that are especially preferred arethose having viscosities at 100 F. between 30 and 300 cps. Generally,the organic fuel forming the oil phase of the blasting agent is presentin amounts sufficient to obtain an oxygen balance between about 30 to+10%, and preferably about -10 to Generally, the organic fuel is presentin amounts of about 2 to 12% and preferably about 4 to 8%, based on theweight of the composition.

It is also necessary to use a lipophilic emulsifier in admixture withthe organic fuel forming the continuous phase in an amount sufficient toform and maintain a stable water-in-oil emulsion. Lipophilic emulsifierswhich can be used include salts of long-chain fatty acids such ascalcium, magnesium or aluminum oleate; sorbitan esters such as sorbitanmonolaurate or monooleate; ethylene oxide condensates of fatty acidssuch as Armour Ethofat manufactured by Armour Industrial Chemical (10.,Division of Armour and (30., aromatic sulfonic acids such as lineardodecylbenzene sulfonic acid; alkyolamides such as Swift F-221manufactured by Chemicals Department, Swift and Co.; triethanolamineoleate (Dominol TO-lOO) manufactured by Dominion Products, Inc.; talloil amides such as the tall oil amide of tetraethylene penta-amide,EZ-Mul, manufactured by Boroid Division of National Lead Co. Generally,at least about 0.25%, by weight emulsifier, based on the weight of thetotal composition, is present in the blasting agent to form a stableemulsion. Larger amounts of emulsifier can be used in the compositionwithout detrimental effect, since it functions as a fuel. However, froma practical standpoint, based primarily on economics, usually not morethan about 4%, and generally not less than about 1%, by weight,emulsifier is used. For most applications the amount of emulsifierpresent in the composition is from about 1 to 2% by weight.

Any suitable means for incorporating gas bubbles in the present blastingagent can be used. For example, gas bubbles can be incorporated bydispersing gas in the blasting agent by direct injection, such as by airor nitrogen injection, or the gas can be incorporated by mechanicallyagitating the composition and beating air therein. However, preferably,incorporation of gas bubbles is accomplished by the addition ofparticulate material such as air-carrying solid material, for example,phenolformaldehyde microballoons, glass microballoons or siliciousglass. The amount of gas bubbles incorporated in the blasting agentresults in a composition containing about 5 to 50% and preferably 10 to35% gas bubbles, by volume.

Alternatively, if desired, conventional fuels can be added to thecomposition as auxiliary fuels. Any conventional fuel that is stable canbe used. Examples of auxiliary metallic fuels, which are especiallypreferred, are aluminum, magnesium, ferrosilicon, ferrophosphorus, aswell as mixtures thereof. Other finely-divided fuels such as coal,sulfur, sugars, vegetable meals or other forms of finely-divided carboncan be used. The total amount of fuel in the composition, e.g. auxiliaryand organic, is adjusted so that the total composition has an oxygenbalance of from about 30 to +10% and, preferably the oxygen balance isbetween about 10 and +0%.

The following specific examples are given for a clearer understanding ofthe invention. These examples are illustrative only and are not to beconstrued as limiting the underlying principles and scope of theinvention.

EXAMPLES l5 Paraffin, corvus oil and the lipophilic emulsifying agentwere heated in the amounts indicated to about F. to form a liquid andthen added to a turbine mixer. Ammonium nitrate, sodium nitrate, aminenitrate (when added) and water were heated in the amounts indicated toabout F. and subsequently added as an aqueous solution to the mixer. Thehot ingredients were agitated to thoroughly mix the composition and forma water-inoil emulsion wherein oil was the continuous phase. Glassmicroballoons were added to the emulsion while it was being agitatedand, thus, uniformly distributed throughout the explosive. Thecompositions were poured in threeand two-inch diameter portions fordetonation.

Examples Ammonium nitrate, percent 60. 0 57.0 53.5 56. 0 51. 4 Water,percent 18.0 18. 0 18.0 18. 0 18.0 Sodium nitrate, percent 15.0 15.015.0 15. 0 15.0 Monomethylarm'ne nitrate, percent 4.0 8. 6Ethylenediamine dinitrate, percent 3.0 6. 5 Glass microballoons/cwt.,percent 3.0 3.0 3.0 3.0 3.0 Corvus oil, percent 2. 0 2. 0 2.0 2v 0 2.0Paraffin, percent 3. 0 3. 0 3. 0 3. 0 3. 0 EZ-Mul (Tall oil amide oitetraethylene pentaamine), percent .0 2. 0 2.0 2.0 2.0 Densityfg/ce.) 1.29 1. 29 1. 29 1. 29 1. 29 Detonation velocity 1 (m./s.):

3-inch. 5, 255 5, 442 5, 442 5, 442 5, 442 2inch Fail 4, 618 4, 918 4,618 4, 916

1 At 40 F, with air confinement.

It can be seen from the above table that the compositions described inExamples 2 to that contain amine nitrates detonated at 2-inch diametersand the detonation velocities of these compositions were higher than thecomposition without amine nitrate that failed to detonate at 2-inchdiameters.

EXAMPLE 6 The procedure described above in Example 5 was repeated exceptthat 8.6% of trimethylamine nitrate was substituted for monomethylaminenitrate. Portions of the composition were loaded at twoand three-inchdiameters and detonated. The composition detonated in each instance withdetonation velocities of the order of those given in Example 5.

We claim:

1. A blasting agent in the form of a water-in-oil emulsion comprisinginorganic oxidizing salt, nitrogen-base salt of an inorganic oxidizingacid and a base selected from the group consisting of (1) acyclicnitrogen bases having no more than two hydrogen atoms bonded to thebasic nitrogen and up to three carbon atoms per basic nitrogen, and (2)phenylamines, water, water-insoluble organic fuel that forms acontinuous oil phase in the blasting agent, lipophilic emulsifier forsaid fuel capable of forming and maintaining a stable Water-in-oilemulsion, and 5 to 50%, by volume, gas bubbles incorporated in saidblasting agent.

2. The product of claim 1 wherein the organic fuel, forming thecontinuous oil phase is a hydrocarbon.

3. The product of claim 2 wherein the nitrogen-base salt is an aminenitrate.

6 4. The product of claim 3 containing solid air-carrying materialcontaining gas bubbles.

5. The product of claim 4 containing 3 to 30% aliphatic amine nitratescontaining up to 3 carbon atoms.

5 6. The product of claim 5 containing solid air-carrying material in anamount sufiicient to obtain to 35%, by volume, gas bubbles in thecomposition.

7. The product of claim 4 wherein the amine nitrate is monomethylaminenitrate.

10 8. The product of claim 4 wherein the amine nitrate isethylenediamine dinitrate.

9. The product of claim 4 wherein the lipophilic emulsifier is a talloil amide of tetraethylene penta-amine.

10. The product of claim 4 wherein the inorganic oxidizing salt isammonium nitrate.

References Cited UNITED STATES PATENTS 3,356,547 12/1967 Berthmann etal. 14992 X 3,431,155 3/1969 Dunglinson et al 149-47 3,471,346 10/1969Lyerly 149--47 3,409,484 11/1968 Minnick 149-92 X 3,459,608 8/1969Ludolphy et a1. 149-92 X 3,447,978 6/ 1969 Bluhm 1492 CARL D. QUARFORTH,Primary Examiner S. J. LECHERT, JR., Assistant Examiner 0 US. Cl. X.R.

